Four quadrant biopsies in regular ranges is the goldstandard in monitoring this disease. The ideal situation for the endoscopist is to visualize cellular structures, which implies having microscopic imaging available. A potential candidate to fill this gap could be confocal fluorescence microscopy (Cellvizio®-GI and Mauna Kea Technologies). To compare the gold standard with the confocal fluorescence microscopy for detection of metaplastic - or intraepithelial neoplastic changes of barrett-suspicious esophageal mucosa this study has been initiated.